#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>

#define LEDOFF  0
#define LEDON   1

int main(int argc, char * argv[])
{
    int fd, retvalue;
    char * filename;
    unsigned char databuf[1];

    if (argc != 3) {
        printf("Error Usage!\r\n");
        return -1;
    }

    filename = argv[1];

    fd = open(filename, O_RDWR);
    if (fd < 0) {
        printf("file %s open failed!\r\n", filename);
        return -1;
    }

    databuf[0] = atoi(argv[2]);     /* 将字符转换为数字 */
    retvalue = write(fd, databuf, sizeof(databuf));
    if (retvalue < 0) {
        printf("LED Control Failed!\r\n");
        close(fd);
        return -1;
    }

    close(fd);

    return 0;
}